2 Corinthians 3:2-6 ESV
You yourselves are our letter of recommendation, written on our hearts, to be known and read by all. And you show that you are a letter from Christ delivered by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.
Such is the confidence that we have through Christ toward God. Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God, who has made us sufficient to be ministers of a new covenant, not of the letter but of the Spirit. For the letter kills, but the Spirit gives life.
ESV: English Standard Version 2016